RU44391U1 - ACOUSTIC ANEMOMETER - Google Patents

Abstract

The utility model solves the problem of expanding the assortment of acoustic anemometers with high sensitivity and a wide range of measurement of flow velocity vector values while reducing design complexity and increasing its reliability. The specified technical result is achieved by the fact that in the anemometer consisting of a computing device, a generator of short pulse signals, an acoustic emitter and receivers whose signals are amplified by appropriate amplifiers and fed to the computing device, the emitter and receivers of acoustic signals are placed in one plane on a supporting structure made in the form of a direct cross, while the emitter is installed in the center.

Description

The invention relates to measuring equipment, namely, devices for acoustic measurement of gas flow parameters and quantities that can be obtained from these data, and can be used in geophysics.

A known acoustic meter of gas flow in pipes, based on measuring the difference in the times of arrival of the emitted acoustic signal to sensors located on and against the gas flow. The meter contains an acoustic system in the form of an emitter of sound signals and microphones as sound detectors that are placed in the measuring tube at a certain distance from each other, as well as an acoustic signal generator through which signals are fed to the sound emitter, and a correlator to which signals from microphones. A continuous tone signal is used as an acoustic signal, a correlation computer is used to calculate the arrival time difference, and to calculate the gas flow rate, it is necessary to know the speed of sound propagation in a given gas medium. The speed of sound propagation is tabulated depending on the temperature of the gas, therefore, the known device is equipped with a temperature sensor (p. US No. 54421212, publ. 06/06/1995).

However, this meter is used only for measuring the flow velocity, and the need for a priori knowledge of the speed of sound significantly complicates both the design of the device and the algorithm of its operation.

A device for determining the magnitude and direction of the airflow vector, consisting of 3 ultrasonic probes and a temperature sensor in combination with an electronic computing circuit for outputting air traffic signals, showing the magnitude and direction of at least three coordinate axes.

The device contains on one central rack three ultrasonic emitters located at an angle of 120 °, and three receivers opposite each emitter on its own rack, and the difference in arrival times is determined by a high-speed clock (US No. 4038870, publ. 2.08.1977 g).

However, separating the clock from the data acquisition system and the use of a pairwise emitter and receiver requires additional calibration.

Closest to the claimed acoustic anemometer for simultaneous measurement of the components of a three-dimensional flow vector, which includes a generator to obtain an oscillating electrical signal; an acoustic emitter for receiving this signal and generating a continuous tone acoustic signal; at least three acoustic receivers for receiving said acoustic signal and subsequently generating an electric signal in response thereto;

a computing device for processing signals to obtain an electrical signal for a generator and at least 3 acoustic receivers. A computing device connected to the temperature sensor processes the incoming signals to determine the velocity vector. The processor collects data at a high amplitude-pulse modulation frequency, for example, 10 kHz, which allows the smallest atmospheric turbulence to be resolved.

However, the use of measuring channels to determine the projection of the velocity vector that are not in the same plane with the emitter complicates both the design and the calculation algorithm, since the task of determining the third projection is associated with the presence of additional receivers and the complexity of the calculation algorithm due to the need to perform additional calculations.

The objective of the invention is to expand the range of acoustic anemometers with high sensitivity and a wide range of measurement of the values of the flow velocity vector while reducing the complexity of the design and increasing its reliability.

The problem is solved in that in an acoustic anemometer consisting of an electric signal generator mounted on a supporting structure of the emitter and acoustic signal receivers located at equal distances from the emitter; a computing device for setting and processing signals and a temperature sensor connected to it, the generator uses short pulse signals, the emitter and receivers of acoustic signals are located in the same plane, and the supporting structure is made in the form of a straight cross, in the center of which the emitter is installed, and acoustic receivers are placed at the ends, while the emitter is additionally equipped with a power amplifier, and the receivers are pre-amplifiers.

The principle of operation of the inventive device is based on measuring the components of the projection of the velocity vector of the gas flow and calculating the modulus of the velocity vector and its directivity.

The block diagram of the anemometer is shown in Fig, on which the axes of the XY coordinate system coincide with the lines of the straight cross, forming a connected XY coordinate system. The anemometer consists of a computing device (WU), a pulse signal generator (GIS) connected to it, a power amplifier (PA) for an acoustic pulse emitter (I), acoustic pulse receivers (Px1), (Px2), (Pu1), (Pu2) located around the emitter (I) at equal distances (L) on the axes of the associated coordinate system XU. The signals of the receivers are amplified by the corresponding preamplifiers (PUx1), (PUx2), (PUU1), (PUU2) and then fed to (VU). The sensor (t) of the outdoor temperature is connected to a computing device (WU).

If an anemometer is used to determine the wind speed vector, the XY plane is horizontal.

As a computing device, for example, an Atmel Mega AVR series microcontroller is used, which has a built-in analog-to-digital converter and timers that allow both the digitization of the signals received at the inputs and the measurement of time

the passage of acoustic pulses from the emitter to the receivers. It is advisable to use, for example, piezoceramic ones as acoustic emitters and receivers, and a resistance thermometer, for example, as a temperature sensor. The supporting structure is a cross, in the center of which a radiator is installed, and at the ends are receivers of acoustic signals.

Note that the layout of the meter with specific constituent elements depends on the requirements for the anemometer and the area of its further use, including the required measurement accuracy of the flow velocity vectors, therefore, for high-precision measurements, wider emitter and receivers and a high-speed processor of the computing device are used.

The inventive anemometer operates as follows. A generator (GIS), controlled by a computing device (WU), generates short, usually rectangular pulses, which, being amplified by a preliminary amplifier (AM), are fed to an acoustic emitter (I) and emitted to the environment. The emitted pulses are received by receivers (Пх1), (Пх2), (ПУ1), (ПУ2), the signals of which are amplified by the corresponding amplifiers (ПУх1), (ПУх2), (ПУу1), (ПУу2) and enter the computing device (WU), which Due to its internal structure and corresponding software, it determines the time of arrival of an acoustic pulse to each of the receivers. If there is a gas flow V, the projections of its velocity vector on the axis of the associated coordinate system will be Vx and Vy, respectively. Denoting the speed of sound propagation as Va, we obtain a system of equations relating the propagation time of an acoustic pulse along the axes of a coupled coordinate system (for example, along the X axis), the distance from the emitter to the receivers L, the projection of the wind speed on the axis of the coupled coordinate system Vx, and the speed of sound in air Va:

The solution to this system of equations is the parameters Va and Vx. The solution to similar equations for a pair of receivers located along the Y axis are the parameters Va and Vy. After obtaining the above parameters, calculate the magnitude of the velocity vector module V as

and the angle of the wind direction in the associated coordinate system and how

as well as atmospheric pressure P as a function of the speed of sound and temperature, constantly measured by a temperature sensor:

P = F (Vα, t)

The calculation functions of all the above parameters are assigned to the computing device. With a time resolution of the computing device of the order of 3 μs, the inventive anemometer provides a speed sensitivity of 0.2 m / s.

Distinctive features of the claimed anemometer in relation to the prototype are: the presence of two pairs of receivers located on the axes of the associated coordinate system in the same plane with the emitter, and the emission of a sequence of short acoustic pulses, which allows you to effectively deal with "spurious" acoustic phenomena caused by the propagation of sound along the carrier designs. The location of the receivers and the emitter in one plane reduces the power requirements of the emitter and simplifies the design and calculation algorithm.

The claimed combination of essential features of the proposed meter leads to a new anemometer that provides high sensitivity and frequency range of the device (up to hundreds of hertz), reliability and reduced operating costs, and at the same time allows the simultaneous determination of direction, flow rate and atmospheric pressure.

Claims (2)

1. An acoustic anemometer consisting of an electric signal generator, emitter and acoustic signal receivers located at a support structure at equal distances from the emitter, temperature sensor and computer system, characterized in that a short pulse signal generator, emitter and acoustic receivers are installed as a generator the signals are located in one plane, and the supporting structure is made in the form of a straight cross, in the center of which is located the emitter, and at the ends - acoustic skie receivers, wherein the transmitter is further provided with a power amplifier, and receiver preamplifiers. 2. The acoustic anemometer according to claim 1, characterized in that the emitter and receivers of acoustic signals are located in a horizontal plane.